Yeah, that should be causing Montreal fans to cry out in terror, even if the injury isn't serious enough for Calvillo to miss Saturday's game against Calgary. Of course, this is a long way from the most severe injury situation that's arisen this week, as Stampeders' QB Drew Tate still isn't throwing, Riders' QB Darian Durant has a walking boot on his sprained foot and Bombers slotback Cory Watson picked up a hamstring injury during practice Wednesday. If Calvillo isn't able to go, though, that might have the largest impact of any of these injuries.

Watson's departure hurts an already-depleted Winnipeg receiving corps, but they have some options to replace him (including talented junior product Brett Carter, currently on the Bombers' practice squad), while Calgary's Kevin Glenn proved in last week's win over Montreal that he's still more than capable of filling in. Durant's injury probably comes the closest to Calvillo's in terms of both his positional significance and the drop-off to his replacement, but at least Saskatchewan backup Drew Willy has thrown 99 CFL passes over the last two years (completing 72, or 72.7 per cent, with five touchdowns and four interceptions). By contrast, Alouettes' backup Josh Neiswander has been with the team since last season, but has never attempted a regular-season pass. Given how steep of a learning curve playing quarterback in the CFL is thanks to the three downs, the 12-a-side game, the bigger field, the expanded pre-snap motion and other quirks, don't expect a great debut from him.

The quarterback's importance to his team also plays a role here. Yes, Durant's been great for the Riders so far, but a lot of their success to date comes from Kory Sheets' record-setting rushing performance. Sheets should play reasonably well regardless of who's under centre, even if the lack of defensive respect for the passing game without Durant may hinder him a bit. That's similar in Calgary, where running back Jon Cornish is just as vital to the team's success as whether it's Glenn or Tate under centre. In Montreal, that's not the case: the Alouettes have the league's worst rushing attack through three weeks, averaging CFL lows in rushing yards per game (61.0) and gain per rush (4.1). That's not all on Brandon Whitaker (or the recently-released Chris Jennings), as Montreal's offensive line has struggled all season, but there isn't much of a run game for Montreal to rely on without Calvillo.

The Alouettes' struggles so far shouldn't be blamed on Calvillo. Yes, he's in his 20th CFL season and his 15th year with Montreal, but he's shown he can still be very effective when given the right chance to succeed. The Alouettes' offensive line has given him no protection thus far, though, conceding 13 quarterback sacks through three weeks (one behind Winnipeg for the league's worst total), and he's still adjusting to the offensive schemes of new head coach Dan Hawkins and new offensive coordinator Mike Miller. There's every reason to believe that Calvillo is still critical to any success this Montreal team will find this year, and the lack of experienced depth behind him following the offseason decision to cut Adrian McPherson and the post-camp decision to jettison Quinton Porter is extremely concerning for a team with a 40-year-old quarterback and an offensive line that's currently leaking like a sieve. This thumb injury may or may not turn into something that causes Calvillo to miss a game, but it should certainly get Alouettes fans worrying about what could happen if he does go down at some point. This team's been terrible on offence thus far, putting up a league-low 227.0 yards per game and just 21.0 points per game, second-worst in the league, but they might be even more atrocious without their star quarterback.